Unfortunately, he was the one who came home from work first, unloaded the dryer and saw this. All he had to say was, "Oh, Cathy. It's ruined." (I felt really bad).
So, like a good wife, I promptly raided his email box to find the original order for his shirt, then reordered the same shirt. It was the least I could do to atone for my screw up--that, or just stay away from the laundry machine!
We looked through everything and could not find what could have possibly ruined the shirt.